VOLUME 19 (Supplement)

Microplastic distribution in surface water and sediments: Water quality dynamics in Laguna Lake West Bay, Philippines

Laguna Lake West Bay is experiencing severe anthropogenic stress compounded by presence of emerging contaminants. This study evaluates the distribution and profile of microplastics (MPs) in surface water and sediment at four principal fishery locations (Talim Island, Muntinlupa, West Bay Center, and Sta. Rosa), sampled from March to April 2025. Following extraction via wet peroxide oxidation (WPO) and dual-stage density separation, particles were characterized using FTIR spectroscopy. The data confirm widespread MP pollution, showing a uniform spatial distribution with no significant localized variation in total abundance (p > 0.05, α = 0.05). Notably, benthic sediments serve as the primary depositional reservoir, containing higher MP concentrations compared to the pelagic zone. Fragment-type particles were the most abundant morphologically across all sites. Compositional analysis identified HDPE, LDPE, and EVA as the principal polymers, indicating that single-use packaging, bottle caps, and fishery-related gear were the likely primary sources. Physicochemical analysis revealed that while most water quality parameters met DENR Class C standards, certain sites exhibited elevated ammonia and biochemical oxygen demand (BOD) levels, indicative of organic pollution. Despite these localized environmental stressors, statistical analyses showed no significant correlation (p > 0.05; α = 0.05) between water quality dynamics and microplastic abundance. These findings highlight the critical threat posed by plastic pollution to the aquatic ecosystems of Laguna de Bay, underscoring the need for strengthened regulatory measures to safeguard ecological stability and public health.